Response of meiofaunal and nematode communities to sewage pollution abatement:a field transplantation experiment

To assess the recovery rate of meiofaunal and nematode communities upon abatement of sewage pollution, a field transplantation experiment was conducted in Tat Tam, which is a non-polluted, shallow subtidal habitat on the southern portion of Hong Kong Island. The sediments used were from one site located in Victoria Harbour that was heavily influenced by sewage pollution, and one site in the outside-harbor area, which was relatively clean. In addition, sediments from Tat Tam were used as a control. Fresh sediments with meiofauna were collected from the aforementioned sites, placed in plastic trays and transplanted to Tat Tam. Sediments were retrieved at the beginning of the experiment and at 1-, 3-, and 8-weeks after transplantation for analysis of the meiofaunal and nematode communities as well as the sediment characteristics. The results showed that the meiofaunal and nematode communities in the control sediments were consistent at the four sampling periods, while it took three and eight weeks, respectively, for the nematode communities from the outside-harbor and inside-harbor sites to become similar to the control. These findings indicated that the relatively poor habitat quality and the nematode community composition in the sewage polluted inside-harbor sediments required a longer time for recovery than samples from the better habitat quality and the nematode community composition in the outside-harbor sediments.

To assess the recovery rate of meiofaunal and nematode communities upon abatement of sewage pollution, a field transplantation experiment was conducted in Tai Tam, which is a non-polluted, shallow subtidal habitat on the southern portion of Hong Kong Island. The sediments used were from one site located in Victoria Harbour that was heavily influenced by sewage pollution, and one site in the outside-harbor area, which was relatively clean. In addition, sediments from Tai Tam were used as a control. Fresh sediments with meiofauna were collected from the aforementioned sites, placed in plastic trays and transplanted to Tai Tam. Sediments were retrieved at the beginning of the experiment and at 1-, 3-, and 8-weeks after transplantation for analysis of the meiofaunal and nematode communities as well as the sediment characteristics. The results showed that the meiofaunal and nematode communities in the control sediments were consistent at the four sampling periods, while it took three and eight weeks, respectively, for the nematode communities from the outside-harbor and inside-harbor sites to become similar to the control. These findings indicated that the relatively poor habitat quality and the nematode community composition in the sewage polluted inside-harbor sediments required a longer time for recovery than samples from the better habitat quality and the nematode community composition in the outside-harbor sediments.